The radius of curvature of an article is commonly measured by direct measurement of the article's diameter, using a micrometer or similar device. Such devices typically measure the distance between two components contacting the article on diametrically opposing sides, using either mechanical or electronic means. The measured distance is then divided in half to provide the radius of the article.
While this method can be accurate, it requires simultaneous access to opposing sides of the article which may not always be accessible. For example, partially buried pipes do not normally permit access to opposing sides of the pipe, and measuring an inventory of tubular stock is often hampered by the lack of access to opposing sides of the tubular stock. Further, not all curves are completely cylindrical in cross-section, but rather may be partial curves such as at the intersection of two planar surfaces.
Various diameter and radius measuring tools are available, but they are generally complex, difficult to use and require conversion tables or calculations to generate a useable measurement. The majority of such tools are “Y” shaped devices that have a base and a yoke formed by two angularly diverging legs that have a 60 degree angle therebetween. A movable probe-bisects the angle and extends outwardly from the base into the area defined by the yoke. A curve to be measured is positioned in the yoke so the legs simultaneously contact the curve at two spaced apart positions. Thereafter the probe is moved outwardly from the base until it contacts the curved surface between the two contact points. The distance the probe moves between the base and the curved surface, plus the radius being measured is the hypotenuse of a right triangle. Because the angles are known, the radius and diameter of the curve can be calculated using known trigonometric formulas.
Yoke type radius measuring devices have disadvantages as well. First, such devices are almost universally constructed using a 60 degree angle because the sine of 30 degrees is 0.5 which leads to simple mathematical calculations. Unfortunately, such devices are unable to measure many articles because the curve to be measured will not fit within the yoke. Yoke type devices defining notches greater than about 60 degrees are not conducive to probe movement and when the probe movement is minimal, an accurate measurement may not be possible. Such minimal probe travel from the base to the curve requires that any delineations between measuring indicia on the probe be closely spaced leading to difficult reading and interpretation. Such minimal movement also necessitates frequent recalibration of the probe position relative to the base to maintain device accuracy. Further, yoke type devices often require an operator to perform mathematical calculations to convert the distance the probe moves into a usable measurement.
What is needed is a device for measuring a circular curve without requiring access to diametrically opposite sides of the article or the article's cross-section, a device with sufficient probe movement to provide an accurate measurement and a device that provides a usable measurement without resorting to conversion tables or calculators.
The present invention provides such a device and resolves various of the aforementioned drawbacks.
My radius measuring tool provides a user friendly device that directly measures the radius of circular curves without accessing diametrically opposed sides of the article, without a need for conversation tables, without calculations and without needing frequent recalibrations. My radius measuring tool has improved accuracy because the probe moves across the V notch rather than bisecting the notch which leads to increased travel and increased accuracy. Further, my radius measuring tool operates on the principle that actual movement of the probe relative to a fixed zero point is equal to the radius of the measured circular curve.
My invention does not reside in any one of the identified features individually but rather in the synergistic combination of all of its structures, which give rise to the functions necessarily flowing therefrom as hereinafter specified and claimed.